Show HN: RE3 – Reversed Engineered GTA3 Source Code

by swatson741 • 2 years ago

129 29 2 years ago

tety• 2 years ago

Can you share some of the tools and methods you used to reverse such a large C++ codebase into readable code?

The history[1] section in the README file contains a description of how they did it. In summary, it seems they debugged GTA3 and wrote their stub implementations until the game was all reimplemented, presumably with only the assets from Rockstar’s GTA3.

[1] https://github.com/halpz/re3?tab=readme-ov-file#history

lstodd• 2 years ago

Well you can look into how DFHack for Dwarf Fortress was redone. It involved a C++ decompiler written in clisp.

Since then Ghidra was released, so the process is somewhat simpler, if not as much *fun*.

Hamuko3• 2 years ago

"GTA 3 and Vice City were originally written in C++," aap explains. "The compiled executables that are shipped are in machine code. So the general task is to go from machine code back to C++.
"Machine code can be (more or less) mapped 1:1 to a human readable form called assembly language, but it's still very tedious to read.
"To go back to C++ is by no means a simple 1:1 mapping, but over the last 10 or so years decompilers have appeared that help with this process.
"So what we typically do is work with the output of the decompiler and massage it back into readable C++. This is sometimes quite easy and sometimes hard, but in any case it's a lot of code and you're bound to make mistakes."
Thankfully, the code for GTA 3 on PS2 and Android includes debug symbols. Debug symbols contain all the extra information needed to debug a game during the development process, but are often stripped out for release executables to avoid bloat. For whatever reason, Rockstar left these symbols in, giving the reverse-engineering team a huge leg-up.
"We were very lucky we had symbols for the games," aap says. "PS2 [GTA] 3 and all the Android releases have names for the global stuff (functions and global variables). This was a huge help and I don't think we'd be anywhere near reversed GTA without them."

https://www.eurogamer.net/how-a-small-group-of-gta-fanatics-...

euazOn• 2 years ago

Im curious, since it seems to be mostly about walking back the one-way-street of C++ to assembly, what’s stopping us from training a ML model to help with decompilation by figuring out patterns in the compilation process? (there has to be a reason, otherwise someone would have done it already)

Hamuko3• 2 years ago

RE3, meaning the project that was shut down because it was just straight up decompiled from Rockstar's binaries?

Pannoniae• 2 years ago

it went to court and they settled, and the repo is still up. take it as you will

crummy• 2 years ago

That must be unusual? I would have thought any settlement would have included "take down the code" as priority #1.

jumploops• 2 years ago

Due to everyone staying home during the start of the Corona pandemic everybody had a lot of time to work on re3 again and we finally got a standalone exe in April 2020 (around 180k lines by then).

This is awesome. I’m curious what other projects owe their success to the pandemic?

plaguna• 2 years ago

mRNA vaccines

Y_Y2• 2 years ago

Zoom, 5g mind control, work-from-home

yieldcrv2• 2 years ago

SPACs

3abiton• 2 years ago

TikTok, unfortunately

iknowstuff• 2 years ago

hmmm this was DMCA'd to hell earlier

yieldcrv2• 2 years ago

clone and move on!

whatever1• 2 years ago

Ok naive question, but how did they reverse engineer the source code comments?

4gotunameagain• 2 years ago

They didn't, they added them in while reverse engineering.

sour-taste• 2 years ago

Also all the other things that wouldn't be present in a pure decompilation, like preprocessor macros.

lyu07282• 2 years ago

Rockstar should've just worked with modders instead of whoever produced the garbage re-masters. Like fans have more respect and love for GTA than anybody working at Rockstar. Fuck this company.

Y_Y2• 2 years ago

That unfortunate release was done by an outside studio who had previously done mobile ports for Rockstar: https://en.wikipedia.org/wiki/Grove_Street_Games

landgenoot• 2 years ago

Isn't this just a fork of the DCMA'ed repository?

The links in the readme still point to https://github.com/GTAmodding/re3

dawidpotocki• 2 years ago

I wouldn't even call it a fork, it's just a mirror with a commit that replaces few links in a README.

webprofusion• 2 years ago

"Reverse Engineered" doesn't mean what you think it means. This is just looks like a copy of the actual code.

colonwqbang• 2 years ago

"to study or analyze (a device, as a microchip for computers) in order to learn details of design, construction, and operation, perhaps to produce a copy or an improved version"

Isn't that what has happened here? They decompiled the program and gave each function and variable a meaningful name, added comments and fixed some bugs.

ThinkBeat• 2 years ago

This is a truly monumental creation.

THe level of effort it must have taken is enormous.

I peeked at the source code expecting what asm - > C reverse engineering tools usually spit out, which is quite a mess, but this is clean and commented.

I stand in awe.

ouraf• 2 years ago

I keep stumbling onto this repo when looking for tools to reverse engineer old Resident Evil games.

Show HN: RE3 – Reversed Engineered GTA3 Source Code

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